使用一般处理程序.ashx

一：访问

访问时要带后缀例如：http://localhost:15343/updateAPK.ashx 

二下载文件，例如作用更新apk的后台

 public class updateAPK : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            HttpResponse Response = context.Response;
            HttpRequest Request = context.Request;

            System.IO.Stream iStream = null;
            byte[] buffer = new Byte[10240];
            int length;
            long dataToRead;
            try
            {
                //获取虚拟目录的物理路径。
                string filepath = context.Server.MapPath("Content/Ship.apk");//待下载的文件路径
                iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,
                    System.IO.FileAccess.Read, System.IO.FileShare.Read);
                Response.Clear();
                dataToRead = iStream.Length;
                long p = 0;
                if (Request.Headers["Range"] != null)
                {
                    Response.StatusCode = 206;
                    p = long.Parse(Request.Headers["Range"].Replace("bytes=", "").Replace("-", ""));
                }
                if (p != 0)
                {
                    Response.AddHeader("Content-Range", "bytes " + p.ToString() + "-" + ((long)(dataToRead - 1)).ToString() + "/" + dataToRead.ToString());
                }
                Response.AddHeader("Content-Length", ((long)(dataToRead - p)).ToString());
                Response.ContentType = "application/octet-stream";
                Response.AddHeader("Content-Disposition", "attachment; filename=" + System.Web.HttpUtility.UrlEncode(System.Text.Encoding.GetEncoding(65001).GetBytes(System.IO.Path.GetFileName("Ship.apk"))));
                iStream.Position = p;
                dataToRead = dataToRead - p;
                while (dataToRead > 0)
                {
                    if (Response.IsClientConnected)
                    {
                        length = iStream.Read(buffer, 0, 10240);
                        Response.OutputStream.Write(buffer, 0, length);
                        Response.Flush();
                        buffer = new Byte[10240];
                        dataToRead = dataToRead - length;
                    }
                    else
                    {
                        dataToRead = -1;
                    }
                }
            }
            catch (Exception ex)
            {
                Response.Write("Error : " + ex.Message);
            }
            finally
            {
                if (iStream != null)
                {
                    iStream.Close();
                }
                Response.End();
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }